Dr. Palmas suggests that different levels of diagnostic sensitivity (1) could help minimize false-positive results. Prospective studies can evaluate this issue and quantify the frequency of misdiagnosis of HIV infection by HIV-1 plasma viral load testing. In the meantime, physicians should use caution in diagnosing HIV infection solely on the basis of a detectable HIV-1 plasma viral load. However, we continue to encourage efforts to rapidly and accurately diagnose acute HIV infection. This is a responsibility for all care providers, not just specialists in the field.

Goodman and colleagues describe the converse situation, in which an undetectable HIV-1 plasma viral load is found in persons who are HIV infected but not receiving antiviral therapy. The authors report that 13 of the HIV-infected patients in their cohort had plasma viral loads less than 400 copies/mL and that 6 had an undetectable plasma viral load on ultrasensitive assay. All of these patients had preserved CD4 cell counts and percentage of CD4 cells and normal ratio of helper to suppressor cells. These persons may become long-term nonprogressors, although they have not had a sufficient duration of follow-up (2). Using HIV-1 plasma viral load testing to diagnose HIV-1 infection can also provide false-negative results. Laboratory data should be interpreted on the basis of the clinical scenario and are not a substitute for vigilant clinical evaluation that combines serologic and plasma viral load testing with clinical follow-up.